Grass Concrete

8/4/2019 Grass Concrete

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So versatile is the GRASSCRETE system that it can often be claimed as a tailored solution

to a range of construction problems from heavy traffic applications to high water flow erosioncontrol.

Across the years, GRASSCRETE has become a generic reference to the process of grass

and concrete paving. Occasionally however, the unique cast on site system is confused with

precast variants.

We hope, with this publication, to provide a definitive guide for GRASSCRETE in all of its

major applications which should enable safe specification without confusion.

CHAPTER ONE

DESIGN PRINCIPLES Part 1 Theory

Part 2 Construction

CHAPTER TWO

TRAFFIC APPLICATIONS Part 1 Earthworks and Sub-base Design

Part 2 Drainage

Part 3 Car ParksPart 4 Access Roads i) General

ii) Emergency

Part 5 Laybys

Part 6 Loading Tables

CHAPTER THREE

EROSION CONTROL Part 1 Reservoir/Flood Defence

Part 2 Storm Channels

Part 3 Flow Rate Tables

CHAPTER FOUR

OTHER APPLICATIONS Tailored Projects

CHAPTER FIVE

MAINTENANCE AND USE Part 1 Use

Part 2 Maintenance

Part 3 Grass Types

Part 4 Remedial Works

CHAPTER SIXINFORMATION FOR THE QUANTITY SURVEYOR

INTRODUCTION

CONTENTS


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PART ONE ~ THEORY

GRASSCRETE is essentially a cellular reinforced concrete slab, the cells being created bycasting around plastic void formers.

The plastic former, manufactured from recycled materials is the culmination of many years ofstudy which has perfected the shape of the pocket and the form and draw of the vacuumforming process. It provides crucially, the strength to accept live concrete loads, yet is thinenough to enable the tops to be easily melted to reveal the voids.

Structural analysis of the finished concrete section is based upon the bending moment of themesh reinforcement contained within the slab, relatively to slab depth, contact area with baseand an assumed allowable ground bearing of 45kN/m2 for its base. By using combinations ofdepth and different mesh types, the system can be tailored to provide the most economicalsolution.

PART TWO ~ CONSTRUCTION

The 600x600mm plastic formers are laid edge to edge over a sand blinded formation to forma continuous layer broken only by a 100mm margin to the edge of each bay and at the pointof each expansion joint.

Once the formers are in position the mesh reinforcement is laid over the former upstands, theindividual 200x200mm upstands of each corresponding to the grid module of thereinforcement. As the mesh drops over the upstand, it is located in position by a spacer, thisintegrally moulded feature fixes the position of the mesh.

Expansion joints are located at maximum 10x10m centres and can be specified in the 3following types:-

Type A - Ambient climates (fig.1)Pre-soaked 25mm wide softwood filler to full depth of system with no sealant.

Type B - Extreme climates (fig.1)

Closed cell 25mm wide polyethylene (PE) foam or bitumen impregnated fibreboard. (It isadvisable to seal the latter type to prevent subsequent chafing).

Type C - Heavy load transference (fig.2)As Type B but incorporating 300mm long x 20mm diameter dowels at 600mm centres with capand de-bond to one end with joint sealed irrespective of filler type (we recommend this type ofjoint for use only in the 150mm thick systems and only for regular load transference.

To Type A & B joints we recommend a 100mm wide trowelled margin to expansion joints. ForType C dowelled joints this should be increased to 150mm.

CHAPTER ONE DESIGN PRINCIPLES


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The concrete mix is of a readily available readymix type and can be identified by the followingdesign mix description

Cement type : Ordinary Portland (sulphate resisting may be used for extreme exposure)

Minimum cement content : 350kgs/m3

Maximum water/cement ratio : 0.55Maximum size aggregate : 10mmRatio sand/total aggregate : 0.45

Control/ batch slump : 100mm general applications50mm steep slopes

Site added admixtures : Superplasticiser to manufacturer s recommendeddosage levels.

Final slump : Flowing:- general applications75-100mm:- steep slopes

Air content : 3% +/- 1 1/2% (higher values can be considered forcompliance with highway related specifications)

The type of superplasticiser used can vary and may slightly increase or decrease the aircontent depending upon the formulation.

The concrete mix is designed to self compact around the plastic formers. Only when layingto the very steepest slopes where the slump is markedly reduced should any form ofcompaction be considered.

During pouring the concrete is drawn level to the tops of the formers by use of rubber bladedsqueegees. This should be the only finish applied. Tamping or brushing is not required.The system is designed to be capable of following most profiles either in the plan shape or

vertical level. The former is simply cut to allow the incorporation of curves etc without steppingto the edges.


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In respect of tolerances, the depth of the concrete is limited by the depth of the plastic former.The level at the surface will therefore generally reflect that of the prepared sub-base.

After the concrete has set and hardened (generally after 48 hours), the former tops areremoved. This is carried out by use of LPG or paraffin (Kerosene) flame guns. Waving theburner across the top of the mould removes the top allowing the side walls to melt down toharmless residue deposited in the base of the void.

Please note that the melting out process does not emit any CFCs and there is only a smallquantity of CO2 evident, the operation being similar in its emission levels to wood burning.

Following the melting operation the voids are infilled with topsoil and then seeded.Consideration should be given to the potential settlement of the topsoil which should beallowed to naturally take place. The seed can therefore be incorporated within a fine topsoiloverlayer if the surface is not to be used immediately.

Alternatively, where immediate use is required the soil levels can be topped up at a later stageafter initially striking flush to the upper concrete level.

For types of seed mix please see the appropriate chapters elsewhere in this publication.

Where gravel infill is used in lieu of topsoil/seed, we recommend the use of a 20-5mm gradingwhich will be less susceptible to displacement than smaller graded pea gravel types.

First trafficking of the surface should be linked to the curing period of the concrete. Underambient conditions and a normal curing process we would recommend the followingguidelines.

After 24 hours - foot trafficAfter 7 days - 40% of design load*After 14 days - 75% of design load*After 28 days - 100% of design load*

* Where regular early use is required we would recommend the incorporation of fibrereinforcement in the concrete mix to harden to the pocket walls.


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Where a slow draining sub-grade such as a cohesive clay is encountered, consideration canbe given to the utilisation of an underlying drainage blanket as part of the overall sub-basedesign. This enables a reservoir head to be formed without weakening the ground bearingcapability (see fig.4).

Please see our separate publication GRASSCRETE STORM WATER MANAGEMENT- THECASE FOR A POROUS PAVING SYSTEM which details the advantages of a sustainable self-draining paving system on new developments.

PART THREE ~ CAR PARKS

A common feature of precast systems is their susceptibility to elephant track under regularloading often rendering them unsuitable for all but the infrequently used car parks.GRASSCRETE however, places no reliance upon grass for stability - a drawback with precast.It can therefore be specified in a wide range of applications.

Another factor in the specification of a grassed car park is the tyre rumble under use, a factorassociated with precast units, which on large areas in particular, can be uncomfortable andcause displacement of units due to the resulting vibration. With its reinforced structureGRASSCRETE does not suffer from such problems.

A typical car park module is 4.8 x 2.4 metres with a 6.0 metre wide access aisle for two waytraffic flow. Long strip casting enables bays of 4.8/5.0 metres and 6.0 metres wide can beconstructed utilising the 100mm wide solid concrete edge as a subtle bay delineation (seefig.5).


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In addition to the general parking provided under fig.5, further delineation can be provided bytransverse strips of concrete formed by the omission of a 200mm part segment of a former.This can be either to the full width of a bay or in a truncated tee format (see fig.6).


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With a natural grassed appearance for the car park, it is also possible to eliminate elementsof an otherwise hard landscape. With no requirement for kerb edges the surface can blendinto the natural landscape. With no need for surface water drainage falls, the surface levelcan follow contours which may be contrary to normal requirements. Taking the naturalappearance a step further, shrubs and trees form a softer natural marker than bollards andcan be easily incorporated into most paving layouts. With its self-draining natureGRASSCRETE can be cast to within 600mm of mature trees. Further advice on root trainingis available on request.

As an alternative finish, GRASSCRETE can be specified with a 20-5mm gravel infill to thepockets without affecting the structural performance of the system, as the pocket fill does notinfluence its load bearing capability.

With no requirement for underlying drainage and no need for perimeter kerbs, existingGRASSCRETE car parks can be extended without worrying about drainage falls. This factorenables car parks to be constructed on profiles which would be otherwise unsuitable for asealed paving system.

PART FOUR ~ ACCESS ROADS

i) General Access

GRASSCRETE is often specified for access routes required to have low ecological or visualintrusion. Its self-draining nature limits surface water run off and enables roads to beconstructed with minimal infrastructure work.

Its low visual intrusion is a virtue which sees it regularly specified on defence projects wheresatellite or aerial identification is often to be avoided.

Another virtue lies in its continuous slab structure which defies vandalism, thereby making itideal for use in prison establishments where an alternative precast type could be lifted for

inappropriate use.

A particular advantage over precast concrete and plastic systems is the lack of differentialsettlement or surface shear under load. This eliminates the need for kerb edge restraint andenables slimmer sub-bases to be considered.

The plan profile of access roads can be varied without stepping to the outer edge, this beingachieved by simply cutting the plastic formers tangental to the edge alignment (see fig.7).


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ii) Emergency Access

A fire and emergency access road fulfils an essential function and should not be compromisedin design by its possible infrequent use. Indeed, it is often the case that a fire access is muchmore regularly used than its designed intent. A common feature is the contractors use of the

surface as a haul road during construction. Under such circumstances it is often subjected tomuch higher loads than a fire appliance would otherwise apply.

A rule of thumb design suggests the specification of a fire pumping appliance for buildings ofup to 3 storeys in height. A typical special equipment tender will now have a gross vehicleweight of up to 13.3 tonnes.

For 3 storeys and above or in intensive residential circumstances, access is likely to berequired for a hydraulic platform which are for UK applications 17 or 22 tonnes in gross vehicleweight. Much larger platforms are however found throughout the world although the point loadin operation is likely to be similar.

The point load is an important feature of platform use where, in the presence of saturatedground conditions, the appliance will be supported on jacking legs. Under such conditions apaving layer of low tensile strength such as a precast system is likely to be punched into thesub-grade causing a loss of stability (see fig.8).

Typical access layouts for operational equipment can be viewed in fig.9.


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A further factor in the specification of a fire access route is the intended first use, particularlywhen considering possible temporary construction activity or routine maintenancerequirements. Precast concrete or plastic systems will generally require a full seasons growthbefore a loading capability is achieved. This can often be a significant hurdle to overcome inprogramming the works.

GRASSCRETE on the other hand can be used immediately once its initial curing period haselapsed (see page 3). If construction activity is likely to introduce deleterious material on tothe surface, the melting of the former tops, soiling and seeding can be held over for a moreappropriate stage in the programme with the surface still usable in the meantime.

PART FIVE ~ LAYBYS

Highways often require laybys to be constructed, which are strictly not for public parking.These can be found in a variety of locations such as CCTV kiosks, camera and lightingcolumns, petrol interceptors, police surveillance pads, wide load contra flows and sky cradleplatforms.

The loading criteria may vary for each application though in the case of the latter twomentioned uses, the loading is significant and for such purposes, our GRASSCRETE GC2scvariant has been designed, permitting high point loads.

With its continuously reinforced structure, GRASSCRETE does not suffer from the lateralspread and settlement encountered with precast systems particularly under the turn in andturn out operation in using a typical trapezoidal layby.

The cast in place process also enables a total flexibility in the layout without the need for akerb edge restraint. Manhole and inspection covers can be easily incorporated as can thejointing up to road kerbs or channels.

The comparatively low surface vibration provided from the level upper surface permitsvehicles to quickly turn on to the area or merge back at speed where busy highways dictatesuch a need.

PART SIX ~ LOADING TABLES

SYSTEM DEPTHREINFORCEMENT

(200 x 200)POINT LOAD

(150x150m contact)*TYPICAL G.V.W. *

GC3

GC3

GC1

GC1

GC2

GC2sc

76mm

76mm

100mm

100mm

150mm

150mm

A142 (6mm diam.)

A193 (7mm diam.)

A193 (7mm diam.)

A252 (8mm diam.)

A252 (8mm diam.)

A393 (10mm diam.)

8.5kN

10.8kN

13.5kN

16.7kN

28.8kN

41kN

3.4 tonnes

4.3 tonnes

10.6 tonnes

13.3 tonnes

30.0 tonnes

40.0 tonnes

*Assumed minimum allowable ground bearing of 45kN/m2, and an interpolation based upontypical numbers of tyre contacts.


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PART ONE ~ RESERVOIR/FLOOD DEFENCE

A significant advantage in the specification of a cellular revetment can be found in the ventingof hydrostatic pressures in an earth slope. This enables much slimmer paving sections to beutilised than would be required for solid paving.

The performance of steeper reinforced grass waterways has been studied at length in theCIRIA Report 16 which identifies a number of key elements to be considered in the designcriteria for a suitable revetment.

From information provided, we can broadly categorise armour layers as follows:-

LIGHTWEIGHT ~ geotextiles/geogrids

INTERMEDIATE ~ non-tied precast concrete blocks

HEAVYWEIGHT ~ cable tied precast blocks and GRASSCRETE

Causes of failure under hydraulic load can be associated with one or more of the followingfactors:-

Change of embankment profile, causing turbulent flow

Loss of grass cover where systems rely on grass for stability

Tail water jump at the base of spillways

Lack of an underlying geotextile layer

Displacement of individual units by vandalism

With Grasscretes continuously reinforced structure, an even upper surface is provided whichoffers a consistent flow signature with no focal points for erosion. There is also no risk ofvandalism to the surface and as such, maintenance inspections can be minimised.

With all waterborne applications we would recommend the use of an underlying geotextile toprevent sub-grade scour in the event of a loss of soil filling to the individual pockets. It shouldbe noted that with a continuously reinforced structure, the deadweight of the armour layermeans that a relatively inexpensive geotextile can be utilised as opposed to the high flowvariants required to prevent precast units from lifting under hydrostatic pressure load. For atypical reservoir cross section (see fig.10).

CHAPTER THREE EROSION CONTROL


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With its traffic bearing capability, GRASSCRETE can be specified as a total armour layer toreservoir bunds with crest access for heavy vehicles being accommodated.

In environmentally sensitive areas such as salt flats etc. the GRASSCRETE pockets can beeither sown with natural flora seed mixes or planted with indigenous rushes.

GRASSCRETES cast on site process often suggests a limitation in the angle to which thesystem can be laid, with the notion of concrete loss during pouring. On the contrary, the ribbedcruciform shape of the plastic former is designed to limit the flow of live concrete enablingslope angles of up to 45 to be accommodated.

PART TWO ~ STORM CHANNELS

Increasing urbanisation makes increasing demands upon the process of controlling stormwater run off. Nowhere is this more evident than in tropical and sub-tropical climates where

heavy rainfall leads to intense run off and the spectre of downstream flooding underinadequate control

It would be encouraging to think that the universal specification of porous paving systems willbe a feature in years to come. The mitigation of run off at source being the best possible cure.In the absence of this approach, there will continue to be a need to accommodate highvolumes of storm water.

In temperate climates the use of storm channels will tend to be associated with overflowchannels for swollen rivers. In such circumstances, the armour layer will be designedaccording to the anticipated erosion, with maximum protection adjacent to the spillway or weir.


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In tropical or sub-tropical climates, the demands are much greater with a prolonged intenseflow being encountered throughout the channels length. To assist in the specialised designwe have compiled a publication - GRASSCRETE; PAVING DESIGN FOR RIVER ANDSTORM CHANNELS which is available on request.

A principle design consideration in developing a channel section is the hydraulic roughness ofthe armour layer. The rougher the surface, the slower the flow, the greater the cross-sectionrequired.

A common misconception is that a grassed surface will increase the hydraulic roughness incomparison to plain concrete. Whereas it is true to say that a sub-critical flow will be slowedby grass stems, such a flow is not the determining factor in the design.

By contrast, a super critical flow will see a different situation occurring. Heavy impounding ofgrass stems will cause them to lay prostrate in a surface thatch, rather than being rougherthan plain concrete,a Mannings n value of 0.03 can be achieved under such conditions (see

fig.11).

A GRASSCRETE channel design can therefore provide the twin features of a natural grassedenvironment during dry season, low flow and a hardened wetland water course for peakseason demand.

PART THREE ~ FLOW RATES

The CIRIA Trials of 1986 detailed in Part One were intended to assist in the production of adefinitive guide for grass reinforcement systems. The subsequent guide Report No 16 wasproduced to create a benchmark for the hydraulic capabilities of available systems.

Under trial was our GRASSCRETE GC2 (150mm thick) system which was structurallyunaffected by the maximum flow rate available to the trial. From the information provided, wehave been able to interpolate the results into a recommendation for each of the Grasscretevariants (see fig.12).


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SYSTEM TYPE REINFORCEMENT DEPTH MAXIMUM FLOW RATE

GC3

GC1

GC2

A142/A193 *

A193/A252 *

A252 *

76mm

100mm

150mm

4.5m/sec

6m/sec

8m/sec

* Relates to British Standard BS4483 References

A142 = 200x200mm grids x 6mm diameter wires weighing 2.22kgs/m2

A193 = 200x200mm grids x 7mm diameter wires weighing 3.02kgs/m2

A252 = 200x200mm grids x 8mm diameter wires weighing 3.95kgs/m2 Fig. 12

CHAPTER FOUR OTHER APPLICATIONS

Tailored Projects

Throughout GRASSCRETES long history, there have been numerous occasions where thesystem has been called into use for previously unspecified roles. GRASSCRETES uniqueadaptability has enabled the product to rise to these new challenges, a few of which aredetailed here.

1) Light Rail Engineering

The ability to tone down the environmental impact of a light rail network through city suburbsis compromised by the engineering considerations in the design. Whilst a grassed track

encourages an environmental solution, a number of important factors need to be considered.

The potential for vandalism if precast elements are used The need to provide access for maintenance vehicles Percolation of surface water when overlaying impervious stage 1 and 2 concrete bases A surface which requires little or no maintenance

Our response to such a brief was the following design which was subsequently incorporatedinto a city centre project (see fig.13).


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Helicopter Landing Pads

Using the essential criteria of a level stable surface and a natural grassed appearance,GRASSCRETE is the ideal solution to the provision of low intrusion helipads. Further benefitis gained by forming the H monolithically within the surface by the elimination of the

corresponding part sections of void former (see fig.14).

Sludge Cake Drying

Perhaps not the most glamorous application for GRASSCRETE and not one for our brochurephotographs. Nevertheless, this particular application proved to be a successful result for theGRASSCRETE system.

In this instance, GRASSCRETE was designed to act as a drainage slab for residual moisturecontained within sludge removed from waste water treatment plants. Using a controlledfiltration, the system allowed the sludge to dry prior to its removal for blending into screenedtopsoils (see fig.15).


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CHAPTER FIVE USE AND MAINTENANCE

PART 1 ~ USE

A question often asked is one relating to the ease of use for both vehicles and pedestrians.Often the questions are influenced by previous experiences with other forms of grassreinforcement.

Vehicular Use

With a flat upper profile and a pocket shape designed to prevent tyre intrusion, vehicles havelittle difficulty in using the surface. The tyre rumble encountered is perhaps the lowest foundamongst concrete systems and is in marked contrast to castellated precast units where thestudded upstands cause discomfort in use and block displacement under vibration.

The integral solid edge margins to each bay prove a subtle definition for the user and isparticularly important for fire access routes. This detail, together with the optional car baymarkers, enables a fully delineated car park to be constructed without the need for paintedlines.

Pedestrian Use

It cannot be expected that a grass and concrete surface will be as easy to walk on as a solidpavement system, particularly for high heel users. That said, the GRASSCRETE system isprobably the easiest grass reinforcement system to walk on. The same advantages that holdfor vehicles apply equally to pedestrian use, the plan shape of the pocket allowing feet to sit

predominantly on concrete. The optional use of bay divisions also aids the process ofdisembarking from vehicles where the first foot is placed on a solid concrete surface.


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PART 2 ~ MAINTENANCE

GRASSCRETE is not a miracle system it grows natural grass. Just as a grassed lawnrequires maintenance, then so will GRASSCRETE albeit to a lesser degree.

Regular vehicular use will trim the grass level down flush to the upper level of the concrete.In a typical car park application, the access routes may show a greater level of grass wear. Itis advisable therefore to apply a routine maintenance programme, particularly to the accesslocations.

A simple maintenance programme can be described as

1. Routinely cut areas subjected to infrequent use to even out growth levels

2. Apply liquid based fertilisers as follows Spring : nitrogen based formulaAutumn: phosphate based formula

Powder or granule based fertilisers should be avoided due to potential for wind drift and

build up on the concrete ribs which can result in scorching of the grass.3. Regular trafficking may result in the soil levels falling slightly in the pockets. It is advisable

to top up levels which are a potential trip hazard. Over filling should be avoided howeveras should compaction of the pocket fill which can injure grass growth.

4. After the construction of the pavement layer and if the surface is not to be usedimmediately, there is benefit to be gained from placing a fine layer of topsoil over thesurface of the concrete. This will enable soil levels to be naturally replenished aftersettlement as well as providing a barrier against solar gain over the newly cast concrete.

PART 3 ~ GRASS TYPES

The actual grass seed specification will depend upon the climatic location or intended use. AsGRASSCRETE is laid throughout the world, the type of indigenous grass will therefore varywith both rhizome or stolon growth types being encountered.

Grass types can be individually tailored for individual projects according to climate, use andaspect. For temperate climates, three amenity based mixes can be utilised to provideflexibility and economy.

Regularly Trafficked Areas

Such applications are generally associated with car parks where the grass will be required togrow under aggressive wear conditions. Normally, the concrete ribs are required to be visible

to provide a surface which is less likely to slurry under use. The combination of these twofactors suggests the specification of a ryegrass based mix which offers erect growth andexcellent wear resistance. Our Mix No 1 suits this purpose.

Infrequently Trafficked Areas

The principle types of use under this category are fire access routes and road verges.

A typical fire access may be located around a high rise building which could place the roadwayin shade. The seed mix should therefore be shade tolerant

A road verge for European applications will be subjected to surface water run off containingrock salt treatment applied to carriageway in winter months. The mix should therefore besaline tolerant.


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Such applications call for minimal maintenance with a carpet of cover generally beingrequired. The combination of these factors suggests the use of a mix with a high proportionof creeping red fescue. Our Mix No 2 is such a type.

Embankment/Slope Protection

A number of different variations upon a common theme can be considered. The mix shouldgenerally provide good root anchorage to prevent pull out.

A dry slope may call for a more manicured approach with a closer grass mix provided bycreeping red fescues. Consideration should be given however to the potential for the surfaceto become slippery under wet conditions.

In waterborne slopes the grass will be required to perform a functional role. Our earlierchapters have described how a stemmed grass can form a protective thatch when laidprostate by heavy water flow. Such a mix will therefore call for a higher proportion of smoothstalked meadow grass. Maintenance of this type should be geared towards the period of

maximum impounding, to achieve the maximum thatching effect, the grass should be left longduring the wet season, our Mix No 3 is designed for such applications.

SEED SPECIFICATIONS

45% Creeping Red Fescue5% Browntop Bent

50% Perennial Ryegrass

20% Chewing Red Fescue45% Creeping Red Fescue

5% Browntop Bent30% Hard Fescue

52% Creeping Red Fescue5% Smooth Stalked Meadow Grass

3% Browntop Bent40% Perennial Ryegrass

MIX SOWING RATE SPECIFICATION APPLICATION

No 1

No 2

No 3

50gms/m2

50gms/m2

50gms/m2

Vehicular ParkingAmenity Areas

Fire AccessShaded low

maintenance areas

Embankments

The difference between a good mix and a poor one is likely to be pence per m? on sowing buta much greater cost on failure. We would therefore recommend the selection of qualitycultivars selected from the upper levels of the Sports Turf Research Institutes tables relativeto the required function.

PART 4 ~ REMEDIAL WORKS

Occasionally it may be necessary to cut out sections of GRASSCRETE to allow for example,a new service trench to be constructed. Very occasionally, damage may occur due to

inappropriate use. Under such circumstances, a remedial repair can be easily accommodatedas shown in fig.16.


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CHAPTER SIX INFORMATION FOR THE QUANTITY SURVEYOR

PREAMBLE(TRAFFIC)

GRASSCRETE cast on site reinforced cellular paving. GRASSCRETE formers typeGC.*, .*mm deep laid on a consolidated sub-base with a 10/20mm sand blindinglayer of sand. Steel mesh reinforcement to BS4483 reference ..*, weighing *kgs/m2

shall be seated upon the integrally moulded spacers. Concrete 30MN/m2 @ 28 days with airentrainment of 3%. 10mm maximum size aggregate and a *mm slump shall be placedaround formers and mesh and levelled to tops of formers. After 48 hours (can be reducedunder suitable conditions), melt exposed tops of formers and fill with soil. Followingsettlement, sow GRASSMIX No * at a rate of 50gms/m2 and top up with fine friable topsoil,

apply fertiliser as necessary.

(EMBANKMENT ~ DRY)

GRASSCRETE cast on site reinforced cellular paving. GRASSCRETE formers typeGC*, *mm deep laid on a 10/20mm blindng layer of sand over a trimmed earth sub-grade with loose debris removed and depressions filled with selected granular material. Steelmesh reinforcement to BS4483 reference ..*, weighing *kgs/m2 shall be seated uponthe integrally moulded spacers. Concrete 30MN/m2 @ 28 days with air entrainment of 3%.10mm maximum size aggregate and a *mm slump shall be placed around formers andmesh and levelled to tops of formers. After 48 hours (can be reduced under suitableconditions), melt exposed tops of formers and fill with soil. Following settlement, sow

GRASSMIX No * at a rate of 50gms/m2 and top up with fine friable topsoil, apply fertiliseras necessary.


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(EMBANKMENTS ~ WATERBORNE)

GRASSCRETE cast on site reinforced cellular paving. GRASSCRETE formers typeGC*, *mm deep laid on a fine dusting of sand over a woven polyester geotextile (seeseparate specification), on a 10/20mm blinding layer of sand over a trimmed earth sub-gradewith loose debris removed and depressions filled with selected granular material. Steel meshreinforcement to BS4483 reference ..*, weighing *kgs/m2 shall be seated upon theintegrally moulded spacers. Concrete 30MN/m2 @ 28 days with air entrainment of 3%. 10mmmaximum size aggregate and a *mm slump shall be placed around formers and meshand levelled to tops of formers. After 48 hours (can be reduced under suitable conditions), meltexposed tops of formers and fill with soil. Following settlement, sow GRASSMIX No * ata rate of 50gms/m2 and top up with fine friable topsoil, apply fertiliser as necessary.

EXPANSION JOINTS

Expansion joints shall be incorporated at 10x10m centres and shall consist of a 25mmpre-soaked softwood filler (25mm close cell foamboard for high temperature zones); forGC3,GC1, GC2 and GC2sc.

Or

Expansion joints shall be incorporated at 10x10m centres and shall consist of a 25mm wideclose cell foamboard filler with 20mm diameter x 300mm long sawn mild steel dowels at400mm centres with cap and de-bond to one end. Joint shall be sealed with a cold appliedsealant; forGC2sc load transferable slabs.

Please note that information is given in good faith, without warranty and subject to alteration without prior notice


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Walker House 22 Bond Street WakefieldWest Yorkshire WF1 2QP

EnglandTel: +44(0)1924 379443 Fax: +44(0)1924 290289

E-mail: [email protected] Web: www.grasscrete.com

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Grass Concrete